The present invention relates to a split hub wheel apparatus for sequential loading, dipping and unloading of material while selectively sealing the apparatus in an air tight environment. More particularly, this invention pertains to the use of a split hub wheel apparatus for the production of high quality fuel oil and motor fuel from oil shale.
Up until the early 1970's liquid hydrocarbon fuels were plentiful and relatively inexpensive. Such fuels were generally derived from crude petroleum found in the Middle East, Far East, United States, Canada, South America and Africa. The onset of the Arab oil embargo of 1973 and the constant turmoil that has persisted in that area since then has served to sharply decrease world oil supplies and concomitantly quadruple energy costs. Furthermore, the energy picture for the future appears to be very grim with the prediction of higher fuel prices and shortages. Aggravating the world energy situation is the continuing increased consumption of petroleum and petroleum based products such as plastics. With each passing year, the dependence of the world on high priced OPEC oil increases beyond all reasonable bounds. Accordingly, great attention has recently been focused on developing alternate energy sources.
Oil shale is America's most abundant energy resource-even bigger than coal. An estimated 28 trillion barrels of oil are locked in shale deposits in at least 13 states, enough to supply the United States with vital liquid hydrocarbon fuel for hundreds of years.
The Green River Formation covering about 17,000 square miles in parts of Colorado, Utah and Wyoming represent about 21/2 times all the oil reserves in the Western world and the Mideast combined. Furthermore, energy experts predict by the year 1990 the shale oil industry will represent a multi-billion-dollar business capable of producing well over 500,000 barrels of oil per day.
Oil shale is neither an oil nor a shale. The term "oil shale" refers to a carbonaceous rock, i.e. marl-a type of limestone, that contains a high molecular weight organic polymer called kerogen. Kerogen is the oil precursor in the oil shale rock. To extract the kerogen from the oil shale, the oil shale must generally be broken into small pieces and heated to pyrolysis temperatures in the range of between about 800.degree. F. (420.degree. C.) and about 1000.degree. F. (538.degree. C.). Oil cannot be derived from oil shale deposits by solely using solvents. The heating of the oil shale and the subsequent production of kerogen is generally carried out in large ovens called retorts or while the oil shale is still underground (in-situ).
Retorting of the oil shale at pyrolysis temperatures causes decomposition of the kerogen and evolution of the oil trapped in the ore, usually in the form of a condensable vapor. If the kerogen is evolved as a vapor, it is condensed to form a thick, viscous black liquid. In this state, the shale oil liquid can generally be used directly for oil or fuel, i.e. as fuel oil. Before it can be refined into more valuable products, the shale oil liquid must generally be treated with hydrogen, i.e. hydrotreating, to remove excess nitrogen and arsenic. Once upgraded, however, the refined products of shale oil are generally superior to those obtainable from the best Saudi Arabian crude oil.
The art of oil shale retorting traces its origins back to as early as 1694 when a patent issued in England to distill oil "from a kind of stone". In the mid 1850's, oil shale was being produced in France, Scotland, Australia, as well as in the United States. More than 3,000 foreign and domestic patents on shale oil retorting processes and associated equipment have since issued.
The major shale oil retorting processes are Paraho, Superior Circular Grate, Union, Tosco II, Lurgi-Ruhrgas and N-T-U. The Paraho, Union and N-T-U processes all involve vertical retorts utilizing hot gas as the heating medium. The Superior Circular Grate and the Tosco II processes use horizontal retorts. The Tosco II process employs a rotating drum with hot ceramic balls supplying the necessary heat. The Lurgi-Ruhrgas process uses a screw mixer and relies on spent shale for process heating.
A lesser known shale oil retorting process, but one employing an air tight kettle of hot liquid and agitation by revolving arms is the Ryan process. The Ryan process, however, suffers from serious drawbacks in that it is subject to explosions and requires a residence time that is considerably longer than the residence time required by the present invention.
The use of rotating retort drums to conduct shale oil processing and oil distillation is well known in the art and is described by many patents, including the following U.S. Pat. Nos. 356,247; 552,456; 634,818; 635,260; 1,183,457; 1,508,578; 1,656,107; 1,695,914; 1,870,901; 1,905,055; 4,105,536 and 4,125,437. These patents concern rotating drums, rather than rotating arms as utilized in in the present invention.
The use of rotating arms to supply agitation during retorting is described in U.S. Pat. Nos. 1,323,681; 1,598,882; 1,614,220; 1,638,217 and 1,681,946. The arms in these patents, however, are used to agitate the retort fluid rather than to unload and dip the shale ore feed and unload the spent oil shale.
U.S. Pat. Nos. 3,443,793; 3,558,100 and 3,612,102 disclose rotary valves having stationary inlet and outlet pipes, disposed at an angle to the axis of rotation of a flow chamber. These patents, however, do not describe the loading, dipping and unloading of material.
U.S. Pat. Nos. 1,461,396 and 2,588,483 describe rotating feeding and dispensing of materials. In both patents, material from a stationary inlet is dropped into a chamber or pocket of a rotating drum. The drum rotates and the material is dispensed by gravity when the pocket or chamber comes into contact with the stationary outlet.
French Pat. No. 13,426 illustrates axial feeding and dispensing using a rotary flow chamber.
U.S. Pat. No. 1,513,504 concerns a centrifugal device. This patent discloses a drum having a rotating shaft. The shaft is partially hollow and serves to both feed and discharge liquids from the drum. Connected to the rotating shaft is a hollow perforated ring. This patent doesn't describe the dipping of fed materials in a liquid bath.